Certainly if we hold these kind of ethics we've got no excuses if an advanced alien race wants to use us in their medical experiments.
I do agree that lab animals aren't a resource in themselves – they're just the currently "next best" model to test in before trying a drug out in humans. In fact, mice are actually quite expensive in terms of time and money – custom-genotype mice can cost hundreds of dollars each, and that's just the up-front purchase price. The overhead of maintaining a mouse line is also quite high, with a huge loss incurred for accidental death or euthanization before they've been used as a model. When many research facilities were first shut down due to COVID lockdown this year, I heard that many labs at my university had to euthanize all their mice as they wouldn't be able to care for them. This represents a loss of months of research time and possibly thousands to tens of thousands of research dollars.
Another thing to consider is that many drug candidates that make it to the animal testing stage don't succeed with safety and/or efficacy testing. According to the FDA, 92% of pre-clinical animal tests actually fail to predict drug effectiveness in humans. This highlights a pressing need for other fail-fast/fail-cheap methods that should precede animal testing, like cell culture methods that could be used as a pre-animal screen.
Thank you for the insightful comment, I'll cite the part that is relevant, since my (very serious) point was indeed that by this logic a more "advanced" being than us would have (by our own morals) the right to conduct medical experiments on us humans, because we are capable of feeling less pain.
If an advanced alien wants to use us in experiments, I doubt they'd care much about what we say on the matter. And for all we know, the aliens might come from a predator background and only consider vicious species as true equals.
It's not even comparable.